Light addressing component gradient gas sensor and preparation and test method thereof

Abstract

The invention discloses a light addressing component gradient gas sensing device and a preparation and test method thereof, the gas sensing device comprises a two-dimensional material conductive channel transferred on a silicon oxide / silicon substrate, and source and drain electrodes and a gate electrode are deposited at two ends of the two-dimensional material channel and on the substrate through electron beam evaporation to prepare a two-dimensional material field effect transistor; preparing a component gradient noble metal nano array by adopting an electron beam inclined deposition technology, and modifying the two-dimensional material field effect transistor; and finally, independently outputting responses of different component nanorod modification positions of the device by using a light addressing technology, and realizing sensing array integration in a single device scale. Adsorption behaviors, dielectric properties and molecular vibration differences of different gas molecules on the gradient array are reflected on optical excitation electric signal response and Raman response of the device, and the device can be used for high-sensitivity recognition of the gas molecules. The device has a wide application prospect in the fields of hazardous gas detection, respiratory gas analysis and the like.

Description

Technical Field

[0001] This invention belongs to the field of trace detection technology and relates to a high-sensitivity, high-selectivity optically addressed composition gradient gas sensor and its preparation and testing methods. Specifically, it relates to a gas sensor based on composition gradient nanostructures and optical addressing technology, as well as its preparation and testing methods. Background Technology

[0002] Two-dimensional material field-effect transistors (FETs) are widely used for trace detection of various molecules due to their advantages such as high sensitivity, real-time detection, low power consumption, and low cost. However, the adsorption selectivity of two-dimensional materials as sensitive surfaces limits their gas sensing applications. Although various modifiers such as nano-metals, oxides, molecules, and polymers have been functionalized onto the surface of two-dimensional materials, it is still difficult to achieve selective and broad-spectrum detection of gas molecules using electronic noses.

[0003] To further improve sensing selectivity, different gas sensors are often integrated into arrays to provide more complete molecular response information. However, in existing sensor arrays, independent and separable testing of individual devices often relies on electrical addressing technology, which occupies a large amount of chip space due to the extremely large number of bonding pads and interconnects, thus reducing array density. At the same time, the complex array fabrication and high R&D costs also create barriers to the application of this technology.

[0004] In recent years, based on the photoelectric effect in materials, optical addressing technology has been developed to locate localized electrochemical response signals in electrolyte-insulator-semiconductor field-effect devices and electrolyte-semiconductor structures by exciting charge carriers to form virtual electrodes or activating electrochemical reactions through light irradiation. This technology allows for the acquisition of sensor array response signals with spatial resolution equivalent to the size of the irradiated light spot, without the need for complex wiring or packaging. Therefore, research on using optical addressing technology to overcome the shortcomings of electrically addressable sensing technology has become a hot topic. Summary of the Invention

[0005] The purpose of this invention is to provide a gas sensor device based on compositional gradient nanostructures and optical addressing technology, which can be integrated into a single device, as well as its fabrication method and sensing and testing method. The inventors designed a two-dimensional material field-effect transistor (i.e., a sensor device) modified with a nanoarray of horizontally varying compositional gradient. By combining this with optical addressing testing technology, the photoexcitation electrical signal response at different spatial locations of the sensor device is monitored during gas adsorption. This allows for the analysis of the relative relationship between the photoexcitation electrical signal responses at different locations. Furthermore, the gas concentration can be analyzed using changes in the sensor device's conductivity (i.e., the kinetic trace of the adsorption process), and different adsorbed molecules can be distinguished using in-situ Raman signals.

[0006] This invention is achieved through the following technical solution:

[0007] A light-addressable composition gradient gas sensor, which is a gas sensor based on composition gradient nanostructures and light-addressing technology, is characterized by comprising a substrate, a conductive channel of two-dimensional material transferred to the surface of the substrate, a field-effect transistor formed by growing metal electrodes at both ends of the conductive channel of the two-dimensional material, and a composition gradient noble metal alloy nanoarray grown on the surface of the conductive channel of the two-dimensional material.

[0008] The substrate has an insulating layer, and the substrate is a silicon wafer, optical glass, quartz substrate, sapphire substrate, ceramic substrate or plastic substrate, and the insulating layer is a silicon dioxide layer.

[0009] Furthermore, the two-dimensional material exhibits a field effect, and the two-dimensional material is graphene, molybdenum disulfide, tungsten ditinide, and their two-dimensional van der Waals materials with up to 20 layers.

[0010] Furthermore, the noble metal alloy nanoarray is a binary noble metal alloy nanoarray, wherein the noble metal is gold, silver, platinum, or palladium. The noble metal alloy nanoarray can excite surface plasmons, and the nanoarray can be nanorods, nanoparticles, or nanopores.

[0011] Furthermore, the composition of the noble metal alloy nanoarray varies in a direction parallel to the direction of the two-dimensional material's conductive channel, and its composition varies in a gradient along the direction of the two-dimensional material's conductive channel.

[0012] Another technical solution of the present invention, a method for preparing the above-mentioned gas sensor device, includes the following steps:

[0013] 1) Markings are prepared on the substrate surface using photolithography and electron beam deposition.

[0014] 2) Using photolithography and transfer methods, a two-dimensional conductive channel is prepared at the marked location on the substrate surface in step 1);

[0015] 3) Using photolithography and electron beam deposition, electrodes are grown at both ends of the two-dimensional material conductive channel obtained in step 2), thereby fabricating a field-effect transistor;

[0016] 4) Using the electron beam tilt deposition method, a noble metal alloy nanoarray thin film with a composition gradient is grown on the surface of the two-dimensional material conductive channel obtained in step 3), thereby obtaining the above-mentioned gas sensor device.

[0017] in,

[0018] The transfer method for preparing the two-dimensional material conductive channel described in step 2) is: mechanical peeling, dry transfer or wet transfer.

[0019] The method for creating a field-effect transistor in step 3) is as follows: A mask is placed over the surface of a substrate with transferred two-dimensional material and fixed on the sample stage of an electron beam deposition system. The beam current is adjusted to be nearly perpendicular to the incident direction. Two noble metals are used as targets (e.g., chromium and gold, or palladium and silver). A first noble metal with a thickness of 5–10 nm and a second noble metal with a thickness of 25–35 nm are sequentially deposited at both ends of the conductive channel of the two-dimensional material. Metal electrodes are grown at both ends of the conductive channel, thereby fabricating a field-effect transistor. The first noble metal electrode is chromium or palladium, and the second noble metal is gold or silver. The electron beam deposition conditions are: DC electron beam, energy 8–12 eV, vacuum degree 4 × 10⁻⁶ eV. -4 The substrate with the transferred two-dimensional material is then cooled with liquid nitrogen. The width of the conductive channel is 50–200 μm.

[0020] The method for preparing composition-gradient noble metal alloy nanoarray thin films described in step 4) is as follows: the two-dimensional material field-effect transistor prepared in step 3) is fixed on the sample stage of a dual electron beam deposition system, two noble metals are used as the target material (e.g., silver-platinum metal), and the chamber of the dual electron beam deposition system is evacuated to 1×10⁻⁶. －4 Below Pa. (See attached) Figure 1 As shown, a baffle is installed 0.3–1.5 mm above the two-dimensional material conductive channel prepared in step 2). The length of the baffle in the direction perpendicular to the substrate should be relatively large, usually not less than 1 cm, to control the deposition of the evaporation beams generated by the two evaporation sources in the opposite region. By adjusting the width w of the baffle and the distance d from the substrate, where w is 0.16–1 mm and d is 0.3–1.5 mm, the incomplete shadow areas generated by the two evaporation sources with a diameter of about 1 cm behind the baffle overlap, thereby continuously changing the ratio of the deposition rates of the two noble metals in the two-dimensional material conductive channel region. The beam inrush angle is adjusted to 80–89 degrees to control the uniform growth rate of the nanostructures of the two metals in the absence of the baffle. This results in a noble metal alloy nanoarray film with a compositional gradient distribution parallel to the direction of the two-dimensional material conductive channel, thus fabricating a compositional gradient gas sensing array.

[0021] The electron beam deposition conditions are as follows: DC electron beam, energy 8–12 eV, vacuum degree 4 × 10⁻⁶. -4 The substrate is then cooled with liquid nitrogen.

[0022] Another technical solution of the present invention is a method for testing gas using the gas sensor device obtained above, characterized by comprising the following steps:

[0023] (1) A laser with periodically varying intensity is focused on the surface of the sensor device prepared above, and then the difference between the frequency channel of the input alternating current and the frequency channel of the laser signal is used to output the conductivity (resistance) and photoexcitation electrical signal of the two-dimensional material conductive channel respectively.

[0024] (2) Gas is introduced into the sensor device to adsorb the gas onto the noble metal alloy nanoarray. The conductive channel region of the two-dimensional material modified with the noble metal alloy nanoarray is scanned by laser to obtain the array response of the photoexcitation electrical signal in the direction of composition gradient change after gas adsorption. The response is compared with the photoexcitation electrical signal obtained in step (1) to distinguish the target gas molecules.

[0025] (3) During the scanning in step (2) above, the conductivity signal of the gas during the adsorption process is collected, and the dynamic trace of the conductivity of the two-dimensional material conductive channel during the gas adsorption process is obtained. Based on this, the concentration of target gas molecules can be analyzed.

[0026] (4) At the same time, when the laser scans the noble metal alloy nanoarray in the sensor device, the Raman signal of the adsorbed molecules excited by the laser is collected.

[0027] (5) The Raman signal of the adsorbed molecule obtained in (4) above and the array response of the photoexcitation electrical signal obtained in (3) above are used to jointly determine the type of adsorbed molecule.

[0028] In step 4), since the noble metal alloy nanoarray in the sensor has surface-enhanced Raman characteristics, the Raman signal of the adsorbed molecules excited by laser can be collected and the array response of the photoexcited electrical signal can be used to determine the type of adsorbed molecules.

[0029] The principle of the composition gradient gas sensor of the present invention for sensing and detecting gases is based on the modulation of plasmon behavior on the surface of noble metal alloy nanoarray by molecular adsorption and / or the enhanced Raman scattering signal of molecules to identify gas molecules in the environment; and further, based on the amount of charge doping generated by molecular adsorption on two-dimensional materials, the concentration of gas molecules in the environment is measured.

[0030] The beneficial effects of this invention are:

[0031] This invention relates to a composition gradient gas sensor that achieves high integration of a sensing array at the single-device scale by combining optically addressed sensing technology with a noble metal nanostructure exhibiting composition gradient changes. Since the conductivity response of the graphene conductive channel and the photoexcitation signal have different characteristic frequencies, their independent outputs can be achieved through different signal frequency channels. By scanning the photoexcitation signal, the adsorption characteristics and dielectric modulation capabilities of the analyte gas molecules on the gradient material can be acquired as their "signature" signal, thereby enabling the identification of different analyte molecules. Furthermore, by using a field-effect transistor to detect the change in conductivity of the entire sensing device during molecule adsorption in real time, the concentration of analyte molecules in the environment can be analyzed. This noble metal nanoarray can be further used to enhance the Raman signal of adsorbed molecules, and combined with the optically addressed response, it further improves the gas sensing selectivity of the device.

[0032] Therefore, the composition gradient gas sensor of the present invention has advantages such as high integration, simple fabrication, small size, and practicality. Furthermore, the gas detection method using this gas sensor can simultaneously perform qualitative and quantitative detection of both gas type and concentration, offering advantages over previous detection methods such as high sensitivity, high selectivity, and rapid detection. Thus, this composition gradient sensor has broad application prospects in hazardous gas monitoring and respiratory gas analysis. Attached Figure Description

[0033] Figure 1 Schematic diagram of the apparatus for fabricating composition gradient nanorod arrays

[0034] Figure 2 Compositional changes of silver-platinum compositional gradient nanorod arrays from the silver-rich side to the platinum-rich side.

[0035] Figure 3 Morphology of silver-platinum composition gradient nanorod array

[0036] Figure 4 Schematic diagram of optical addressing detection for silver-platinum composition gradient nanorods.

[0037] Figure 5 The resistance signal and photoexcitation electrical signal during gas adsorption

[0038] Figure 6 Normalized photoexcitation electrical signal responsivity of different gas molecules along the gradient direction Detailed Implementation

[0039] The following is in conjunction with the appendix Figure 1-6 The embodiments and examples illustrate the present invention in detail, but should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above description should be included within the scope of protection of the present invention.

[0040] The composition gradient gas sensor of the present invention comprises a substrate, a conductive channel of two-dimensional material transferred to the surface of the substrate, a field-effect transistor formed by growing metal electrodes at both ends of the two-dimensional material, and a composition gradient noble metal alloy nanoarray grown on the surface of the conductive channel of the two-dimensional material.

[0041] Example 1

[0042] Fabrication of composition gradient gas sensor device

[0043] The fabrication of a functionalized graphene field-effect transistor sensor device using a silver-platinum composition gradient nanorod array includes the following:

[0044] The silicon dioxide / silicon wafer, serving as the substrate, was ultrasonically cleaned and dried sequentially with acetone, anhydrous ethanol, and deionized water. Cross-shaped markings were then prepared on the cleaned substrate through spin-coating of photoresist, photolithography, development, deposition, and resist removal. First, graphene was deposited on copper foil using chemical vapor deposition to form a graphene / copper foil structure, which was then cleaned by immersion in acetone. Next, the cleaned graphene / copper foil was placed on a spin coater and spin-coated with polymethyl methacrylate (PMMA) at 2000 RPM. The PMMA was then heated at 80°C for 5 minutes to cure, resulting in a thickness of 300 nm. This formed a PMMA / graphene / copper foil composite layered structure. The resulting composite layered structure was then placed in a plasma cleaner with the copper foil side facing up. Oxygen plasma etching was used to completely remove the incomplete graphene adhering to the back of the copper foil, yielding a clean PMMA / graphene / copper foil composite layered structure.

[0045] Next, the clean composite layered structure obtained above is floated in an ammonium persulfate solution with a concentration of 0.05-0.1 mol / L, with the copper foil facing down, and the copper layer is completely etched away to obtain a polymethyl methacrylate / graphene bilayer structure.

[0046] Then, after cleaning the polymethyl methacrylate / graphene bilayer structure with deionized water, the polymethyl methacrylate / graphene bilayer was transferred onto the aforementioned dried and marked substrate, and then treated at 150°C for 1 hour, followed by treatment in vacuum for 24 hours.

[0047] Next, the processed polymethyl methacrylate / graphene structure with substrate was immersed in acetone and isopropanol in sequence to remove the polymethyl methacrylate layer and obtain a two-dimensional material with transferred graphene, namely a graphene / silicon dioxide / silicon wafer structure.

[0048] Multiple graphene conductive channels were fabricated by spin-coating a negative photoresist onto a graphene / silicon dioxide / silicon wafer, followed by photolithography, development, plasma etching, and photoresist removal.

[0049] Then, photoresist was spin-coated onto both ends of the graphene conductive channel, followed by photolithography, development, deposition, and resist removal to fabricate electrodes. Chromium and gold were used as targets for deposition, and the deposition rate was controlled to be... 5nm of chromium and 35nm of gold are deposited to form a graphene field-effect transistor.

[0050] Next, the graphene field-effect transistor was fixed on the sample stage of the dual electron beam deposition system. A baffle was placed above the graphene conductive channel on the substrate surface, with a baffle width w and a distance d from the substrate of 0.5 mm and 1.0 mm, respectively. Then, using silver and platinum as targets, the chamber of the dual electron beam deposition system was evacuated to 1 × 10⁻⁶. －4 Below Pa;

[0051] Next, the sample stage was cooled with liquid nitrogen, and an inclined growth method was used. The beam inrush angle was adjusted to 86 degrees, and the deposition rate of the silver evaporation source (crucible No. 1) was controlled. The deposition rate of the platinum evaporation source (crucible No. 2) was: By controlling the uniform growth rate of nanostructures from two metals in the unbaffled region, a composition-gradient nanorod array film was deposited in a region parallel to the direction of the graphene conductive channel (see...). Figure 1 This allows for the fabrication of graphene field-effect transistor sensor devices (i.e., gas sensor devices) functionalized with silver-platinum composition gradient nanorod arrays.

[0052] The elemental analysis results for the silver-platinum composition gradient nanorod array prepared in Example 1 are as follows: Figure 2 As shown in the figure, the normalized relative atomic contents of silver and platinum change continuously along the direction of the source-drain electrode connection, indicating that the nanorod array prepared above exhibits a gradient change, forming a composition gradient nanorod array.

[0053] Figure 3 The images show scanning electron microscope (SEM) images of the nanorod array prepared in Example 1 on the silver-rich and platinum-rich sides. As can be seen from the images, the nanorod morphology is relatively consistent within the compositional gradient region. In the left image, the nanorods on the silver-rich side are relatively thinner and have smaller spacing, while in the right image, the nanorods on the platinum-rich side are thicker and have larger spacing. In the middle compositional gradient region, the nanorod morphology is an intermediate state between the two aforementioned characteristics, gradually changing with the continuous change in atomic ratio. This indicates that the nanorod arrays formed by the two metals exhibit a regular gradient change.

[0054] Example 2

[0055] Methods for detecting gases using composition gradient gas sensors

[0056] The dual electron beam deposition system with the gas sensor prepared in Example 1 fixed was placed in a gas test chamber sealed with a transparent quartz glass cap for gas sensing performance testing. After being flushed with synthetic air, nitrogen dioxide gas with a concentration of 100 ppm was introduced into the gas test chamber.

[0057] like Figure 4 As shown, this is a schematic diagram of optical addressing detection using silver-platinum composition gradient nanorods. Specifically, a laser beam with periodically varying intensity, modulated by a chopper, is irradiated onto the surface of the gas sensor device prepared in Example 1. The laser spot diameter is less than 2 μm. A 389 Hz laser is scanned onto the silver-platinum nanorod array of the gas sensor device, generating a 389 Hz signal on the transistor. This is because the time required to generate the photoexcitation signal is much shorter than the period of the laser intensity change, so the photoexcited signal on the graphene field-effect transistor will change at the same frequency.

[0058] Figure 5 The figure shows the resistance signal and photoexcitation signal during gas adsorption. The lock-in amplification method is used to track the chopping frequency in real time and extract the frequency component from the signal of the graphene field-effect transistor. The left side of the figure is the resistance signal during gas adsorption, and the right side is the photoexcitation signal during gas adsorption. It can be seen that an independent photoexcitation signal can be output in response to the laser irradiation area on the graphene field-effect transistor.

[0059] The moving sample stage allows the laser spot to perform a linear scan on the device in 2μm steps, and the response values ​​of different regions are further obtained from the time-domain signal, enabling optical addressing detection of the photoexcitation electrical signal on the device. By combining the array responses of the photoexcitation electrical signal and the Raman signal on the device and comparing them, the types of adsorbed molecules can be jointly determined.

[0060] Figure 6 This refers to the normalized photoexcitation electrical signal responsivity of different gas molecules along the gradient direction. Through the above experimental process, the adsorption behavior and dielectric modulation behavior of different gases on the compositional gradient silver-platinum nanorod array were tested. Based on the differences in the adsorption and dielectric modulation behaviors of different gases, the characteristics of the gas molecules are reflected by the "signature" signal. For example, the "signature" signals of nitrogen dioxide, carbon monoxide, and ethanol molecules on the silver-platinum compositional gradient nanorod modified graphene field-effect transistor are as follows: Figure 6 As shown, the left and right sides represent the fundamental frequency component and the second harmonic component of the photoexcited electrical signal, respectively.

[0061] from Figure 6As can be seen, the composition gradient gas sensor device prepared in Example 1, when used for gas adsorption, showed good repeatability of the response distribution when the same gas was adsorbed, while the responses when different gases were adsorbed were significantly different, which can be used to distinguish these three gases. The figure also shows that by recording the "signature" signal of the sensor device for various gas molecules and comparing it with the signal of the unknown gas, effective detection of unknown gas types can be achieved.

[0062] Therefore, it can be considered that the gas sensor device prepared by the present invention and the gas sensing and testing method of the present invention can be used to conveniently detect different types of gases. Thus, the sensor device and detection method of the present invention can perform gas detection in some special environments.

[0063] This invention provides an optically addressed composition gradient gas sensor and its fabrication and sensing testing method. It achieves high integration of a sensing array within a single device, enabling convenient simultaneous detection of the concentration of target gas molecules in the environment, as well as the different gas types of various gas molecules. This sensor offers advantages such as simple structure, ease of operation, and high sensitivity. Furthermore, it exhibits good selectivity and high accuracy in gas detection. Therefore, the composition gradient gas sensor of this invention has broad application prospects in hazardous gas monitoring and respiratory gas analysis.

Claims

1. A light-addressable composition gradient gas sensor, which is a gas sensor based on composition gradient nanostructures and light-addressing technology, characterized in that, It includes a substrate, a two-dimensional material conductive channel formed on the surface of the substrate, a field-effect transistor made by growing metal electrodes at both ends of the conductive channel of the two-dimensional material, and a noble metal alloy nanoarray modified on the two-dimensional material.

2. The gas sensor according to claim 1, characterized in that, The substrate has an insulating layer and is made of silicon wafer, optical glass, quartz, sapphire, ceramic, or plastic.

3. The gas sensor according to claim 1, characterized in that, The two-dimensional material exhibits a field effect, and the two-dimensional material is graphene, molybdenum disulfide, tungsten ditinide, and their two-dimensional van der Waals materials with up to 20 layers.

4. The gas sensor according to claim 1, characterized in that, The noble metal alloy nanoarray can excite surface plasmons, and the nanoarray can be a nanorod, nanoparticle, or nanopore.

5. The gas sensor according to claim 1, characterized in that, The nanoarray is formed of a noble metal alloy, and the composition of the nanoarray varies in a direction parallel to the direction of the conductive channel of the two-dimensional material, and its composition varies in a gradient along the direction of the conductive channel of the two-dimensional material.

6. A method for fabricating an optically addressed composition gradient gas sensor according to any one of claims 1 to 5, characterized in that, Includes the following steps: 1) Markings are prepared on the substrate surface using photolithography and electron beam deposition. 2) Using photolithography and transfer methods, a two-dimensional material conductive channel is prepared at the marked location on the substrate surface in step 1); 3) Electrodes are fabricated at both ends of the two-dimensional material conductive channel in step 2) using photolithography and electron beam deposition to fabricate a field-effect transistor; 4) Using electron beam tilt deposition, a composition gradient noble metal nanoalloy array thin film is modified on the surface of a two-dimensional material conductive channel, thereby forming the above-mentioned composition gradient gas sensor device.

7. The preparation method according to claim 6, characterized in that, The transfer method in step (2) can be mechanical peeling, dry transfer, or wet transfer. In step (2), the substrate with transferred two-dimensional material is spin-coated with photoresist, photolithography, development, plasma etching, and resist removal to prepare multiple two-dimensional material conductive channels; In step (3), the substrate with the two-dimensional material channel is spin-coated with photoresist, photolithography, development, deposition, and resist removal to prepare the electrode. The deposition step uses chromium and gold as the target material, and the deposition rate is controlled to be... Deposit 1-10 nm chromium and 20-100 nm gold.

8. The preparation method according to claim 6, characterized in that, Step 4) includes the following steps: (4-1) Fix the above two-dimensional material field-effect transistor on the sample stage of the dual electron beam deposition system, and place a baffle above the two-dimensional material conductive channel on the substrate surface. (4-2) Place the two metals as targets on the sample stage and evacuate the chamber of the dual electron beam deposition system to 1×10⁻⁶. －4 Below Pa; (4-3) The sample stage containing the two metals mentioned above is cooled with liquid nitrogen. The inclined growth method is adopted, and the beam inrush angle is adjusted to 80-89 degrees. The growth rate of the nanostructures of the two metals is controlled to be consistent in the unbaffled area. A nanoarray thin film is deposited in the conductive channel region of the two-dimensional material, thereby forming a composition gradient gas sensor device in which the composition change direction of the alloy nanoarray is parallel to the direction of the conductive channel of the two-dimensional material.

9. A testing method, comprising testing gas molecules using an optically addressed gas sensor as described in any one of claims 1 to 5 or an optically addressed gas sensor prepared in any one of claims 6 to 8, characterized in that, The steps include the following: (1) A laser with periodically varying intensity is focused onto the surface of a gas sensor. Then, the difference between the frequency channel of the input alternating current and the frequency channel of the laser signal is used to output the conductivity (resistance) and photoexcitation signal of the two-dimensional material conductive channel, respectively. (2) Gas is introduced into the gas sensor device, so that the gas is adsorbed on the noble metal nanoarray and the conductive channel. The laser in (1) above is used to scan the conductive channel region of the two-dimensional material modified with the noble metal nanoarray, thereby obtaining the array response of the photoexcitation electrical signal in the direction of the component gradient change after gas adsorption, which is used to distinguish the target gas molecules. (3) During the scanning in step (2) above, the conductivity signal of the gas changes with time during the adsorption process is collected to obtain the kinetic trace of the conductivity of the two-dimensional material conductive channel in step (1) during the adsorption process, which can be used to analyze the concentration of target gas molecules. (4) At the same time, the surface-enhanced Raman characteristics of the noble metal nanoarray in this gas sensor are used to collect the Raman signal of the adsorbed molecules excited by laser. (5) The array response of the adsorbed molecule Raman signal obtained in step (4) and the photoexcitation electrical signal obtained in step (2) is used to determine the type of adsorbed molecule.

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